The present invention relates to a manufacturing method of a composite type thin-film magnetic head with a reading head element for reproducing data from a magnetic medium such as a magnetic disk and with a writing head element for recording data into the magnetic medium.
A conventional manufacturing method of such composite type thin-film magnetic head is as follows.
First, on an under layer which has been deposited on a substrate, a lower shield layer and a lower insulation or gap layer (G1) are sequentially deposited and patterned. On the lower gap layer (G1), a magnetoresistive effect (MR) element which is one example of the reading head element and lead conductor layers connected to the MR element are then formed. An upper insulation or gap layer (G2) is deposited to cover the MR element and the lead conductor layers. Then, the upper gap layer are partially removed by ion milling to form via holes used for externally connecting or leading the lead conductor layers after a conductive material is filled therein at a later manufacturing step.
Thereafter, an upper shield layer which also serves as a lower pole layer of the inductive writing head element is formed and a pole insulation or gap layer (G3) of the inductive writing element is formed to cover the upper shield layer. Then, the pole gap layer (G3) is partially removed by ion milling to form a back gap hole used for connecting magnetic poles of the inductive element at their backside after a magnetic material is filled therein at a later manufacturing step. The gap layer material which was deposited in the via holes when forming the pole gap layer (G3) is also removed by this ion milling.
As will be understood from the above description, the upper gap layer (G2) and the pole gap layer (G3) are formed in different manufacturing steps. Also, the thickness of the upper gap layer (G2) and the pole gap layer (G3) differ with each other. Thus, the via holes used for externally connecting or leading the lead conductor layers of the MR element and the back gap hole used for connecting the magnetic poles of the inductive element cannot be made in the same ion milling process.
Furthermore, since the back gap hole is made in the manufacturing step executed after the manufacturing step of the via holes, it is necessary that the via holes are filled to a partial depth with material such as NiFe which is used for forming the upper shield layer in order to protect their, bottom surfaces from ion milling. However, this partially filled material may still remain after a conductive material is filled in the via hole to make via hole conductors causing the electrical resistance of whole lead conductors connected to the MR element to increase.
U.S. Pat. No. 5,700,380 discloses a method for simultaneously forming such via holes and back gap hole in the same wet etching process by using a single photomask.
However, this method is a wet etching method and uses etchant. Thus, in order to simultaneously etch insulation material layer with different thickness to make holes with different diameters, it is required to carefully set up the size of openings in the photomask for via holes and back gap hole in consideration of etching time etc. Therefore, manufacturing process control becomes very difficult.
It is therefore an object of the present invention to provide a manufacturing method of a composite type thin-film magnetic head, whereby via holes used for externally connecting or leading lead conductor layers of a reading head element and a back gap hole used for connecting magnetic poles of an inductive writing head element can be easily formed in the same manufacturing process.
According to the present invention, a manufacturing method of a composite type thin-film magnetic head with a reading head element and an inductive writing head element, includes a step of forming the reading head element and its lead conductor layers on a first insulation layer which is formed on a first shield layer, a step of forming a second insulation layer to cover the reading head element and the lead conductor layers, a step of forming a second shield layer on the second insulation layer, a step of forming a third insulation layer to make a magnetic gap between magnetic poles of the inductive writing head element, and a step of forming via holes used for externally connecting the lead conductor layers and a back gap hole used for connecting the magnetic poles of the inductive writing head element at their back sides. Particularly, according to the invention, the via holes and back gap hole forming step is executed by reactive ion etching (RIE) for simultaneously removing the second insulation layer and the third insulation layer located at the via holes and the third insulation layer located at the back gap hole.
Since RIE etching rate of the insulation layer or layers to be etched greatly differs from that of the stop layer which is located under the insulation layer or layers and exposed during etching, the insulation layer or layers with different thickness can be simultaneously and extremely easily etched by RIE.
Furthermore, since the back gap hole and the via holes are formed simultaneously, it is not necessary to fill the via holes to a partial depth with material used for forming the upper shield layer in order to protect their bottom surfaces from etching. Thus, the via hole conductors can be made of conductive material only, resulting the electrical resistance of the whole lead conductors connected to the reading head element to keep quite low.
It is preferred that the via holes and back gap hole forming step includes forming a resist pattern with first openings at the via holes and a second opening at the back gap hole, executing RIE for simultaneously removing the second insulation layer and the third insulation layer located within the first openings of the resist pattern and the third insulation layer located within the second opening of the resist pattern, and removing the resist pattern.
It is also preferred that the method further includes a step of forming a fourth insulation layer on the third insulation layer, and a step of forming a coil for driving the inductive writing head element on the fourth insulation material by plating a conductive material, the via holes being simultaneously filled with the plated conductive material.
According to the present invention, also, a manufacturing method of a composite type thin-film magnetic head with a reading head element and an inductive writing head element includes a step of preparing a substrate, a step of depositing an under layer on the substrate, a step of forming a first shield layer on the under layer, a step of forming a first insulation layer to cover the first shield layer, a step of forming the reading head element and its lead conductor layers on the first insulation layer, a step of forming a second insulation layer to cover the reading head element and the lead conductor layers, a step of forming a second shield layer on the second insulation layer, a step of forming a third insulation layer to make a magnetic gap between magnetic poles of the inductive writing head element, a step of forming a resist pattern with first openings at via holes used for externally connecting the lead conductor layers and a second opening at a back gap hole used for connecting the magnetic poles of the inductive writing head element at their back sides, a step of executing RIE for simultaneously removing the second insulation layer and the third insulation layer located within the first openings of the resist pattern and the third insulation layer located within the second opening of the resist pattern, and a step of removing the resist pattern.
It is preferred that the method further includes a step of forming a fourth insulation layer on the third insulation layer, and a step of forming a coil for driving the inductive writing head element on the fourth insulation material by plating a conductive material, the via holes being simultaneously filled with the plated conductive material.
Preferably, RIE is executed by using a fluorine gas as an etching gas. The fluorine gas is more preferably CF4, SF6 or mixed gas of them.
It is preferred that the lead conductor layers have a multi-layered structure of a Ta layer, a Cu layer and a Ta layer, or that the lead conductor layers have a single layer structure a Cu layer or an Au layer.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.